1. Field of the Invention
The present invention relates to an electrolytic capacitor and a fabrication method therefor, the electrolytic capacitor forming a dielectric layer by anodizing an electrode on a surface thereof. More particularly, the invention relates to an electrolytic capacitor featuring control of decrease of electrical insulation caused by crystallization of the dielectric layer in anodizing the electrode, and decreasing leakage current in an electrolytic capacitor.
2. Description of the Related Art
Recently, miniaturization of electronic machines has been bringing about a demand for a small-sized capacitor of great capacitance.
Capacitors having high capacitance are proposed as disclosed in JP-A-5-121275, such as an electrolytic capacitor employing titanium as an electrode and forming a dielectric layer of titanium oxide by anodizing the electrode, or as disclosed in JP-A-11-312628, which discloses an electrolytic capacitor forming a dielectric layer of oxide of metal by anodizing an electrode which employs valve metal composed by sintering powder of valve metal such as aluminum, tantalum, niobium, or titanium, on a surface of the electrode. By the way, the valve metal has the ability of rectification and anodization.
However, when the dielectric layer of oxide of the metal is formed on a surface of the electrode by anodizing the electrode which employs a valve metal composed of a sintering powder of valve metal such as aluminum, tantalum, niobium, or titanium, as mentioned above, the oxide of metal is easily crystallized in anodizing the electrode. Consequently, the electrical insulation of the dielectric layer decreases and leakage current in the electrolytic capacitor increases.